>The Great Orion nebula and the filters
Some shots from Sofia. A very bright sky place. Zenith sky brightness info (2015): SQM 19.13 mag./arc sec2 Brightness 2.41 mcd/m2, Artif. bright. 2230 μcd/m2, Bortle class 6.
However I think that with the LED lights nowadays it is much worse as I can see only the 7 bright stars of Orion.
So I did another comparison of different filters to compare which one is best for my observations.
You can notice that the IR image gives the most stars, as most of the artificial LED lights do not emit IR. However IR is less then 20% of the QE of the sensor and we do not have much details here. The best details and colours we have with the UHC-S as it is narrow band for hydrogen and oxygen. The nebula is reach of those elements. The general light pollution filter (Omegon city lights filter) is also good but my one do not have AR coating and cast some glows. However it is my default choice when shooting at sky with any kind of pollution. It is more universal then UHC-S and I can use it for galaxies as well. Here is the place to check your sky : light pollution map
No fake :) My filters tested with my hand made spectrum analyser and looks good. The light pollution filter cuts all the yellow. UHC-s cuts IR but pass blue light.
For my last trip to the Rodopa mountain I decided to cross the limits and to target an object that is hard to believe that a non-professional equipment could catch.
While cleaning up my PC I found sequences of shots of Virgo galaxy cluster taken during springs of the last 2 years. Those were attempts to shot this object, but I was not satisfied with the result and left them.
I recently bought a pocket spectroscope for laboratory use. You can find it at Ali for 5$. It is with glass prism and well build. So I did some test to use with a telescope but did not
http://www.deepskywatch.com/deep-sky-hunter-atlas.html This is an amazing resource. Detailed atlas of all the sky with NGC and IC objects.
Reading a new product that claims to be 100x time more powerful then conventional telescope, I realise that this is just an astrograph with a digital camera that is doing stacked images and show them trought eyepiece or App.